The present invention relates to the packaging industry and to the plastics moulding industry.
It is aimed more specifically at the dispensing of fluid substances: liquids, emulsions, gels, particularly cosmetic or pharmaceutical, conveyed by pressure into a discharge duct the outlet of which is closed automatically in the absence of pressure, so as to avoid deterioration of the substance remaining in the duct and to ensure that the discharge orifice remains clean. It relates most specifically to closure means employing an elastic diaphragm pierced with a slit.
At rest, the walls of the slit press elastically against one another and close the duct. When a dispensing push-button controlling an aerosol valve or a pump is pressed, or if pressure is applied to a container with compressible flexible walls, such as a tube or pouch, sealed by a stopper equipped with such a duct, the substance ejected under pressure parts the walls or lips of the slit so that it can be dispensed. As soon as the pressure ceases, the slit closes back up and closes the discharge duct.
Such a self-closing device is described particularly in the BOUET French patent number 1 351 565 in its application to flexible bottles or tubes.
According to this patent, the dispensing slit is cut in a thin wall that closes the neck and is formed at the time of moulding from the material of the container. When this device needs to be adapted to a push-button or to a stopper that is screwed on or forcibly inserted into or onto the neck of a container, then a material that can withstand the mechanical stresses of fitting and retaining the stopper or of actuating the push-button must be used to form the body. Such material does not satisfy the elasticity requirements of the dispensing slit. It is therefore necessary to use two different materials for the slit and for the body. It has already been proposed, for example in documents EP 0 743 259 A and 0 442 379 A, for a container stopper comprising a slit membrane to be produced by a two-shot injection-moulding method. However, a slit diaphragm such as this needs a very special and wide configuration of stopper which is well suited to the dispensing of highly viscous liquids or pastes (such as a toothpaste or gel) but is rather ill-suited to the dispensing of more fluid substances, especially those whose release is usually controlled by a system of the aerosol valve type, for which a dispensing nozzle that consists of an elongate tubular passage is preferred. In the prior art, a nozzle of this kind is illustrated by document GB 1 472 178, and consists of a passage moulded in the body transversely to an axial central duct (sitting on the hollow pump- or valve-actuating stem), the entire assembly being produced by moulding in a body which also has an upper surface for pressing on and a peripheral skirt.
If there is the desire to equip such a nozzle with a self-closing slit, the solution of producing a slit diaphragm by two-shot injection moulding is not suitable, as has been seen. From another viewpoint, if the nozzle is made separately and as a single piece with an end part that comprises the self-closing slit made of a material that is flexible enough for this, then the problem of incorporating the slit-comprising nozzle into the body of the container arises. The problem is that if such a nozzle is simply inserted into a housing in the body, then the retaining forces need to be higher than the forces tending to expel the nozzle under the pressure of the fluid substance being dispensed. This leads to the need for precise dimensioning of the nozzle and of the housing in order to ensure correct retention without deformation of the nozzle. It is difficult to achieve such precision under mass-production industrial moulding conditions, particularly given gradual mould wear.
The object of the invention is a self-closing dispenser which does not exhibit such drawbacks and lends itself well to industrial manufacture at competitive cost.
The subject of the invention is a manual dispenser of fluid substances using pressure, which closes automatically in the absence of pressure, having a push-button for controlling an aerosol valve or pump type, or a stopper for a compressible flexible-walled container type, of the kind which has an elastically deformable self-closing dispensing slit incorporated by moulding into a relatively rigid body, characterized in that the slit is made at one end of a one-piece nozzle made up of an elongate tubular element made of a relatively flexible and elastic material, which is incorporated by moulding into the said body.
The tubular element advantageously ends in a wall through which the said self-closing slit partially passes; advantageously, this wall has a dome-shaped interior face, and it may have a flat exterior face.
It is advantageous for the slit to be formed in a slit bulging head of the nozzle, which head is clear of the body and extends the shape thereof, so as to leave the material of the nozzle free to act elastically without the constraint of being closely surrounded by the rigid material of the body.
Advantageously, the body has an axial duct into which the nozzle or an extension thereof opens non-axially; the body also has an upper surface for pressing on and a peripheral skirt, and is designed to have an axial direction of release from the mould.
As a preference, the nozzle points upwards and is designed so as to make an obtuse angle with the said axial direction, so as to make moulding easier, as will be seen later.
In practice, the nozzle may be made of an elastomer of the ethylene-vinyl acetate type, and the body may be made of a polymer of the polypropylene type.
Another subject of the invention is a method of manufacturing such a dispenser, characterized in that the nozzle is first moulded on its own, and then transferred into the body mould so that it can be incorporated into the body when the dispenser is moulded, and the end of the nozzle of the dispenser thus formed is then slit, either in the mould or as a separate operation.